Voltage regulator



July 10, 1962 R (:OOLEY 3,044,008

VOLTAGE REGULATOR Filed Oct. 15, 1958 AMPLIFIER INVENTOR. Robert 12Conley ATTORNEYS starting at other than the minimum value.

3,044,008 VOLTAGE REGULATOR Robert D.' Cooley, Litchfield, Conn.,assignor to The Superior Electric Company, Bristol, Conn., a corporationof Connecticut Filed Oct. 13, 1958, Ser. No. 766,751 9 Claims. c1. s2343.s

I the tubes appreciably lengthens the tube life by minimizing the surgestrain on the filaments.

An object of the present invention is to provide an automatic voltageregulator which upon starting, gradually increases its output voltagefrom a minimum or zero value to the approximately regulated value beforeautomatic regulation of the output voltage commences.

, Another object of the present invention is to provide an automaticvoltage regulator as above set forth in which, in case of power failureand then resumption, the output voltage starts at a minimum or zerovalue and gradually builds up to its regulated value.

A further object of the present invention is to provide an automaticvoltage regulator for achieving the above objects which is simple indesign, relatively economical to fabricate, easy to operate and reliableeven over extended periods of use.

In achieving the above objects, there is provided a voltage regulatorincluding a motorized adjustable transformer having its inputconnectible to a source of electrical energy (such as 120 volts A.C.)and its output serving as the output of the regulator. A sensing circuitsenses the deviation of'the output voltage from its selected value andproduces a signal that directs (through an emplifier) the movement ofthe motor to vary the transforming ratio of the adjustable transformerto change the output voltage and hence maintain it within prescribedlimits of its desired value.

In order to achieve the prevention of instantaneous voltage rise from aminimum value to the selected value from appearing at the output of theregulator, there is provided a control means which serves to direct theenergization of the motor to cause the output voltage to be graduallyincreased from a minimum value to the preselected range. Additionallythere is provided in the control circuit, relays which preventconnection between the output terminals and the output of the adjustabletransformer until the minimum value is reached to thereby prevent theoutput voltage from being connected to the output of the adjustabletransformer during This control means includes a plurality of relays anda pair of switches positioned to operate at selected positions (andhence output voltages) of the adjustable transformer, as will behereinafter more specifically explained, in order to enable the motor tobe energized without any voltage appearing at the output of theregulator and to enable the output voltage to increase from a minimumvalue to the regulated value. After the output voltage reaches theregulated value, the control circuit is rendered inoperative to controlthe adjustable transformer until there oc- Uniteti States Patent Ofificecurs either a manual cessation of the regulator or until a powerfailure, at which time the control circuit upon 3,044,008 Patented July10, 1962 being manually energized gradually increases the output voltagefrom a minimum value to the selected value.

Other features and advantages will hereinafter appear. In the drawing:The sole figure is an electrical schematic diagram of the automaticvoltage regulator of the present invention.

Referring to the drawing, the regulator is generally indicated by thereference numeral 10 and includes a pair of input leads 11 and 12connected to the primary side 13 of an adjustable transformer 14 havinga secondary winding 15 on which a movable brush 16 is operable. Thebrush 16 is connected to be driven by an output shaft of a motor 17 (theshaft not being shown and the connection being mechanical as illustratedby the dotted line connection between the brush and motor).

The motor is reversible and has a pair of fields 18 and 19 electricallyinterconnected through a phase shifting mechanism consisting of acondenser 20 and a resistor 21.

In-phase energization of the winding 18 with out-ofphase energization ofwinding 19 causes the motor to rotate and move the brush 16 to decreasethe output value of the voltage from the secondary winding 15, whileinphase energization of the winding 19 and out-of-phase energization ofthe winding 18 cause a reverse movement of the motor and hence brush 16to increase the output voltage of the transformer 14.

The automatic regulating circuit of the regulator is indicated by thereference numeral 22 and includes a sensing means having a bridge 23 andan amplifier 24, the latter being energized from the input by a pair ofleads 25, though it may be energized from the output of the regulator ifdesired. The bridge 23 is preferably of the non-linear type which is inbalance at a selected voltage and the output voltage of the transformer14 through a pair of leads 26, 27 is compared therewith, so that adeviation therebetween produces a signal which varies in polarity andmagnitude with the signal being fed to the amplifier through the leads28, 29. The amplifier in turn controls the in-phase energization ofeither the winding 18 or 19 through the leads 30 and 31.

The adjustable transformer 14, motor 17 and the automatic regulatingcircuit are components well known in the art and though a specificembodiment of them has been disclosed it will be appreciated that otherwell known types of automatic regulators may be employed.

In the specific embodiment of the control circuit of the presentinvention for achieving the above set forth objects, there is provided anormally open switch 32 positioned to be operated by the brush 16 at itsminimum or zero voltage position and a second normally open switch 33positioned to be operated by the brush 16 when the brush is on thewinding 15 to produce a voltage within the preselected automaticregulating range. Dotted lines are connected to the switches 32 and 33and terminate adjacent the brush 16 at the position the brush must be toactuate the switches.

The control circuit further includes a normally open start button 34, anormally closed stop button 35 and relays 36 through 41 inclusive. Eachof the relays has either one or two switches, one being present inrelays 36 and 38 and two being present in the other relays, with theswitches being shown in the deenergized position of the relays. Therelays are electrically connected together and to the other elements andit is to be noted that the relay 41 is located between the outputwinding 15 of the transformer and output terminals 42 and 43 of theregulator so that unless the relay 41 is energized, no voltage appearsat the output terminals.

With the elements as shown, the input'energized and the start button 34being pressed, the down coil 18 of the motor is initially in-phaseenergized to position the brush 16 at its minimum value prior to anyvoltage appearing in the output terminals, and when the minimum value ofthe output voltage from the transformer is reached, the output of theregulator is connected. Then the output voltage is gradually increasedto the preselected value at which time the control circuit releasescontrol of the transformer.

This is accomplished in the following manner: When the input leads 11and 12 are energized, the relay 3%} is energized closing its switch 33aand this relay is maintained energized whenever voltage appears at theinput. in addition current flows through switch 37a, in-phase throughthe down coil 18 and out-of-phase through the up coil 19, tocause thebrush to move to its minimum position (which is preferably slightlyabove zero voltage) and at this position, the switch 32 is closed. Uponthe switch 32 being closed, the starting button 34' is manually closedand current flows to the relay 36 through the normally closed stopbutton 35 energizing the relay 36 and closing the switch 36a to providea holding circuit for the relay 36 bypassing the starting button 34which can then be released to return to its normally open position. Inaddition to energizing relay 36, relay 37 is also energized through theswitch 32 and the switch 381:. Similarly relays 39 and 41 are energizedthrough the switch 32 and the switch 38a. This causes opening of theswitch 37a breaking the circuit to the down coil 18.

The up coil 19 is then in-phase energized through a switch 40a and 39awhich causes the motor to begin advancing the brush 16 to increase theoutput voltage. It will also be apparent that energization of relay 41connects the terminals 42 and 43 to the secondary of the transformer 14so that the transnformer voltage now appears at the output of theregulator.

The up coil 19 is maintained energized until the brush reaches aposition on the winding 15 which produces a voltage within the range ofthe selected output voltage and at this position the switch 33 isclosed. After the brush during this movement has moved away from theswitch 32, the switch opens; however, a holding circuit for the relays37, 39 and 41 is established through switch 36a, switch 37b, switch 38a.

Upon the switch 33 being closed by the brush 16, relay 40 is energizedthrough switch 3%. This breaks the circuit to the up coil 19' by reasonof changing the position of switch 40a and a circuit is establishedthrough this switch 441a and a lead 44 to the amplifier 24. Theamplifier and sensing means now control the movement of the motor andhence serve to regulate the output voltage to maintain it within thedesired range. A holding circuit for the relay 40 is established throughthe switch 401) and the switch 39b and hence the switch 33 need not bemaintained closed by the brush 16. Thus as the regulator performs itsnormal function of regulating with the regulating circuit in control,all the relays are energized and both switches 32 and 33 are open.

If it is desired to stop the regulator manually, the button 35 ispressed opening the holding circuit to the relay 36, opening switch 36a,which breaks the holding circuit for the relays 37 39 and 41. Relay 39being deenergized, opens switch 3% deenergizing the relay 40. Upon relay37 being deenergized switch 37:: closes, energizing the down field 18and the brush is moved to its minimum output position.

It will be appreciated that only an instantaneous opening of the switch35 is required to break the holding circuit for relay 36 and thus breakthe other circuits. Also when relay 41 is deenergized when the button 35is depressed, the output voltage from the secondary 15, as it decreases,does not appear at the output terminals of the regulator. If voltagestill remains at the input terminal the output voltage of thetransformer automatically decreases to its minimum value to be ready tobe gradually increased again.

In the event of a power failure during automatic regulation, the outputvoltage is immediately decreased to zero and operation of the startbutton is required to bring the output voltage from its minimum value tothe preselected value. The relay 38 becomes deenergized by the powerfailure and opens switch 385) which opens the hold ing circuits forrelays 3'7, 3) and 41 and relay also be comes deenergized. Even thoughthe relay is energized when power resumes, the down coi 1?; of .113motor will be energized through the switch 31 until the switch 32 closesand the start button 3- 1 is closed to cause the other relays to beenergized in the above disclosed manner and the output voltage toincrease from its minimum value to its preselected value.

In order to cause cessation of energization of the motor at its minimumposition and to prevent travel of the brush beyond both limits oftravel, two normally closed switches 45 and 46 are provided. The switch45 is electrically connected in the line to the down coil 12; while theswitch is connected in the line to the up coil 29. These swit arepositioned to be actuated by the brush when the brush reaches thepositions at which the dotted lines connected to each switch terminate.Thus as the brush travels downwardly to decrease the transformer outputvoltage, it first closes switch 32 and then, while maintaining closedthis switch, opens switch 45. Accordingly when the switch 45 opens themotor is deenergized and the control circuit is ready to graduallyincrease the output voltage after operation of the starting button 34 byenergizing the up coil 19.

The switch 46 is positioned beyond the switch 33 in the upward path oftravel of the brush 16 and in the event, through malfunctioning of oneof the components, the up coil drives the brush into engagementtherewith, it deenergizes the up coil. The motor is capable of rotatingeven with one coil open as happens when either of the switches 45 or 46is open and of moving thebrush 16.

While there has been shown six relays, it will be appreciated that alesser number having more switches may be utilized in place of it, forexample relays 37, 39 and 41, since they are either energized ordeenergized together, may be combined into one relay if desired. It isalso contemplated to have an indicator light for indicating when thereis no output voltage and this may be advantageously, for example,connected from one input line to the other through the unused (upper)contact of switch 36a.

It will accordingly be appreciated that there has been disclosed aspecific embodiment of an automatic voltage regulator which preventsinstantaneous increase of voltage from a minimum value to thepreselected voltage range from appearing at the output of the regulator,either resulting from intentionally starting the regulator or fromresumption of power after a power failure. This is accomplished by acontrol circuit having interacting relays which disconnect the outputterminals of the regulator from the adjustable transformer output untilthe transformer output reaches a minimum value. Then the outputterminals are connected and the output voltage is gradually increased tothe desired value at which time the control circuit shifts control ofthe adjustable transformer to a typical automatic voltage regulatorsensing circuit and amplifier.

Variations and modifications may be made within the scope of the claimsand portions of the improvements may be used without others.

I claim:

1. A voltage regulator comprising an input connectiblc to a source ofelectrical energy, an output, an adjustable voltage means connectedbetween the input and output for adjusting the output voltage,regulating means for sensing the deviation of the output voltage from apreselected value and operable to direct the voltage means to maintainthe output voltage within a selected range of the value, and a controlcircuit for causing the output voltage to attain its preselected rangeonly after it has been'increased gradually from a minimum value, saidcircuit including means connected to the voltage means for normallyenergizing said voltage means to reduce the voltage therefrom, means forrendering said reducing energizing means inoperative when the regulatingmeans controls the voltage means, and means for causing said renderingmeans to become ineffective upon a disruption of power from said sourcewhereby upon a resumption of power the energizing means causes thevoltage means to be energized to reduce its output voltage, said controlcircuit being connected to said input for obtaining electrical energytherefrom and including means connected between the input and output foropening the output whenever said reducing energizing means controls thevoltage means.

. 2. A voltage regulator comprising an input connectible to a source ofelectrical energy, an output, an adjustable voltage means connectedbetween the input and output for adjusting the output voltage,regulating means for sensing the deviation of the output voltage from apreselected value and operable to direct the voltage means to maintainthe output voltage within a selected range of the value, and a controlcircuit for causing the output voltage to attain its preselected rangeonly after it has been increased gradually from a minimum value, saidcircuit including means connected to the voltage means for normallyenergizing said voltage means to reduce the voltage therefrom, means forrendering said reducing energizing means inoperative when the regulatingmeans controls the voltage means, means for causing said rendering meansto become ineffective upon a disruption of power from said sourcewhereby upon a resumption of power the energizing means causes theVoltage means to be energized to reduce its output voltage, and meansoperated by the voltage means for ceasing energization of the voltagemeans at a predetermined minimum value of voltage therefrom, saidcontrol circuit being connected to said input for obtaining electricalenergy therefrom and including means connected between the input andoutput for opening the output whenever said reducing energizing meanscontrols the voltage means.

3. A voltage regulator comprising an input connectible to a source ofelectrical energy, an output, an adjustable voltage means connectedbetween the input and output for adjusting the output voltage,regulating means for sensing the deviation of the output voltage from apreselected value and operable to direct the voltage means to maintainthe output voltage within a selected range of the value, and a controlcircuit for causing the output voltage to attain its preselected rangeonly after it has been increased gradually from a minimum value, saidcircuit including means connected to the voltage means for normallyenergizing said voltage means to reduce the voltage therefrom, means forrendering said reducing energizing means inoperative when the regulatingmeans controls the voltage means, means for causing said rendering meansto become ineffective upon a disruption of power from said sourcewhereby upon a resumption of power the energizing means causes thevoltage means to be energized to reduce its output voltage, meansoperated by the voltage means for ceasing energization of the voltagemeans at a predetermined minimum value of voltage therefrom, and meansfor energizing the voltage means to increase the voltage therefrom afterthe cessation means has stopped energization of the voltage means, saidcontrol circuit being connected to said input for obtaining electricalenergy therefrom and including means connected between the input andoutput for opening theoutput whenever said reducing energizing meanscontrols the voltage means.

4. A voltage regulator comprising an input connectible to a source ofelectrical energy, an output, an adjustable voltage means connectedbetween the input and output for adjusting the output voltage,regulating means for sensing the deviation of the output voltage from apreselected value and operable to direct the voltage means to maintainthe output voltage within a selected range of the value, and a controlcircuit for causing the output voltage to attain its preselected rangeonly after it has been increased gradually from a minimum value, saidcircuit including means connected to the voltage means for normallyenergizing said voltage means to reduce the voltage therefrom, means forrendering said reducing energizing means inoperative when the regulatingmeans controls the voltage means, means for causing said rendering meansto become ineffective upon a disruption of power from said sourcewhereby upon a resumption of power the energizing means causes thevoltage means to be energized to reduce its output voltage, meansoperated by the voltage means for ceasing energization of the voltagemeans at a predetermined minimum value or" voltage therefrom, means forenergizing the voltage means to increase the voltage therefrom after thecessation means has stopped energization of the voltage means, meansoperated by the voltage means for ceasing energization of the voltagemeans by the increasing voltage means after the voltage from the outputhas reached the preselected range, and means operable after thecessation of the increasing voltage energizing means, for transferringcontrol of the voltage means to the regulating means, said controlcircuit being connected to said input for obtaining electrical energytherefrom and including means connected between the input and output foropening the output whenever said reducing energizing means controls thevoltage means.

5. A voltage regulator comprising an input connectible to a source ofelectrical energy, an output, an adjustable voltage means connectedbetween the input and output for adjusting the output voltage,regulating means for sensing the deviation of the output voltage from apreselected value and operable to direct the voltage means to maintainthe output voltage within selected limits of the value and a controlcircuit for causing the output voltage to attain its preselected rangeonly after it has been increased gradually from a minimum value, saidcircuit including means connected to the adjustable voltage means fornormally energizing said adjustable voltage means to reduce the voltagetherefrom, means for rendering said first means inoperative when theregulating means con trols the adjustable voltage means, and a manuallyoperable svvitch means for causing said rendering means to becomeinelfective and for shifting control of the voltage means to thereducing energizing means whereby the voltage means is energized toreduce the voltage therefrom, said control circuit being connected tosaid input for obtaining electrical energy therefrom and including meansconnected between the input and output for opening the output wheneversaid reducing energizing means controls the voltage means. I

6. A voltage regulator comprisingan input connectible to a source ofelectrical energy, an output, an adjustable voltage means connectedbetween the input and output for adjusting the output voltage,regulating means for sensing the deviation of the output voltage from apreselected value and operable to direct the voltage means to maintainthe output voltage within selected limits of the value and a controlcircuit for causing the output voltage to attain its preselected rangeonly after it has been increased gradually from a minimum value, saidcircuit including means connected to the adjustable voltage means fornormally energizing said adjustable voltage means to reduce the voltagetherefrom, means for rendering said first means inoperative when theregulating means controls the adjustable voltage means, a manuallyoperable switch means for causing said rendering means to becomeineffective and for shifting control of the voltage means to thereducing energizing means whereby the voltage means is energized toreduce the voltage therefrom, and switch means positioned between thevoltage means and the output and normally being open, said means beingclosed when the regulating means controls the voltage means and beingopen by operation of the manually operable switch means, whereby thevoltage means is disconnected from the output of the regulator when thereducing energizing means controls the voltage means.

7. A voltage regulator comprising an input connectible to a source ofelectrical energy, an output, an adjustable voltage means connectedbetween the input and output for adjusting the output voltage,regulating means for sensing the deviation of the output voltage from apreselected value and operable to direct the voltage means to maintainthe output voltage within a selected range of the value, and a controlcircuit for causing the output voltage to attain is preselected rangeonly after it has been increased gradually from a minimum value, saidcircuit including means connected to the voltage means for normallyenergizing said voltage means to reduce the voltage therefrom, means forrendering said reducing energizing means inoperative when the regulatingmeans controls the voltage means, means for causing said rendering meansto become ineffective upon a disruption of power from said sourcewhereby upon a resumption of power the energizing means causes thevoltage means to be energized to reduce its output voltage, and switchmeans positioned between the voltage means and the output and normallybeing open and connected with the rendering means to be closed by therendering means upon operation thereof.

8. A voltage regulator comprising an input conneetible to a source ofelectrical energy, an output, an adjustable voltage means connectedbetween the input and output for adjusting the output voltage,regulating means for sensing the deviation of the output voltage from apreselected value and operable to direct the voltage means to maintainthe output voltage within selected limits of the value and a controlcircuit for causing the output voltage to attain its preselected rangeonly after it has been increased gradually from a minimum value, saidcircuit including means connected to the voltage means for normallyenergizing said voltage means to reduce the voltage therefrom, meansconnected to the voltage means which upon energization controls saidvoltage means to increase the voltage therefrom, and means operable bythe voltage means at a predetermined value for shifting control of thevoltage means from the reducing energizing means to the increasingenergizing means, said control circuit being connected to said input forobtaining electrical energy therefrom and including means connectedbetween the input and output for opening the output whenever saidreducing energizing means controls the voltage means.

9. A voltage regulator comprising an input connectible to a source ofelectrical energy, an output, an adjustable voltage means connectedbetween the input and output for adjusting the output voltage,regulating means for sensing the deviation of the output voltage from apreselected value and operable to direct the voltage means to maintainthe output voltage within selected limits of the value and a controlcircuit for causing the output voltage to attain its preselected rangeonly after it has been increased gradually from a minimum value, saidcircuit including means connected to the voltage means for normallyenergizing said voltage means to reduce the voltage therefrom, meansconnected to the v0 tage means which upon energization controls saidvoltage means to increase the voltage therefrom, means operable by thevoltage means at a predetermined value for shifting control of thevoltage means from the reducing energizing means to the increasingenergizing means, and normally open switch means positioned between thevoltage means and the output of the regulator and interconnected withthe increasing energizing means to be closed upon control of the voltagemeans by the increasing energizing means.

References Cited in the file of this patent UNITED STATES PATENTS1,326,355 Lehr Dec. 30, 1919 1,804,317 Champlin May 5, 1931 2,407,072Gittings et al Sept. 3, 1946 2,619,630 Stone Nov. 25, 1952 2,839,718Luftman et al. June 17, 1958

